I'm quite knowledgeable, perhaps I can help.
Let's start at the beginning. You run XP on an ancient POS computer (I assume). You didn't say you purchased a new computer so I am assuming that you are going to try and install Win7 on that same computer running XP. If that computer is more than 3 years old, don't proceed any further. You may be able to find new Win7 hardware drivers for some of your components but not all.
Download and run this before proceeding to determine if your box can be upgraded to Win7 and to get an idea of some of the problems you may encounter:
https://www.microsoft.com/en-us/download/details.aspx?id=20
Moviemaker is a Microsoft product and is compatible with win7, 8, 8.1 and eventually Win10.
If you are able to upgrade to Win7 as advised in the above link, go ahead and install Win7. If you need to buy a new computer in order to install win7, I'd wait for Win10 to be released and then purchase a new system that has that OS installed. Win10 will be a more familiar environment. Win7 is now a little behind the times (but still a very good OS). Win8 takes a few weeks to get used to and Win10 will revert back to a more familair WinXP, Win7 look & feel.
Sorry to be a bit of a downer, but anyone still running XP, needs a new system before upgrading. Both the OS and the chipset on the motherboard are no longer supported by the manufactures, Microsoft and third party hardware/software vendors.
You will find your upgrade options going forward with that hardware very limited.